This invention relates to machines for forming round bales of crop material and has particular reference to the wrapping of bales formed in such machines with a flexible binding filament such as conventional baling twine.
In recent years, the practice of harvesting crop material, such as hay or the like, by forming it into large rolls through the use of large roll or round balers, has become increasingly popular. Typically such a machine is moved through a field, receiving crop into a bale forming chamber where it is rotated and is compacted as it accumulates and until a bale of the desired size has been formed. With bales formed in such manner, the need for some type of binding to hold the bale together in its generally cylindrical configuration after it has been discharged from the baling machine, has been recognized from the outset. Accordingly, it has become conventional, as the final phase of formation of a bale in a rotary baler, to continue rotating the bale after it has attained essentially the desired size, while introducing to the periphery of the rotating bale the free end of a length of twine that is anchored in the rotating mass of crop material, so that the length of twine may then be fed and guided relative to the rotating bale to form a binding around the bale in a pattern dependent upon the manner in which the twine is guided with respect to the axial dimension of the rotating bale. The twine is typically fed from a container under appropriate tension through a guide tube or arm whose twine dispensing extremity is shiftable along the axial dimension of the bale.
A variety of techniques and mechanisms for controlling movement of the twine guiding arm have been used, ranging from a simple rope tied to the dispensing arm to be manually pulled by a baler operator for shifting the discharge end of the arm along the axial dimension of the bale, to surprisingly complex mechanical, electrical and even fluid powered arrangements. Most of these twine wrapping devices have typically required the attention during wrapping of the bale of the baler operator and some continuing manual control by him over the movement of the twine dispensing arm. For example, U.S. Pat. No. 4,022,120 teaches movement of the guide tube by means of a reversible electric motor, which is energized to run in either direction or is de-energized by manipulation of a manual switch by the operator of the baler.
Automatic twine wrappers that serially undertake the various steps of the twine wrapping cycle without any operator involvement have also been used in the art.
Operators and manufacturers of the more recent large roll forming machines quickly realized that the less time required for the twine wrapping cycle, the more time there would be for gathering crop material from the field to form completed crop rolls. Therefore, round balers have been the focal point of many ideas for developing twine wrapping means or apparatus that will appreciably decrease the amount of time required for the twine wrapping cycle, as well as active operator involvement in the cycle. Regardless of whether the twine wrapping apparatus is manual, powered or automatic, the time required to complete the cycle is directly a function of the amount of time it takes to dispense the binding material about the periphery of the completed crop roll. When only a single dispensing means is used to oscillate across the bale forming region to dispense binding material, the time required will necessarily be longer than if multiple dispensing means of some types are used to bind the full length of a completed crop roll. Accordingly, the use of multiple elongated dispensing tubes has been proposed which oscillate simultaneously across distinct portions of the entire length of a completed crop roll whereby the length of time required for the twine wrapping cycle to be completed, is substantially decreased. Other multiple twine dispensing means have twine dispensing arms which all are arranged to oscillate across the full width of the bale in a manner to apply overlapping strands of baling twine upon a bale in the bale chamber. In this arrangement individual loops of each individual twine may be spaced further apart so that again a twine wrapping cycle of reduced length is obtained. Obviously, when multiple dispensing tubes are used, these multiple dispensing tubes require the corresponding use of multiple strands of binding material.
The operation of the multiple dispensing apparatus must be synchronized so that the strands of binding material dispensed from the elongated dispensing tubes are wrapped about the completed crop roll and severed at approximately the same instant so that the twine wrapping cycle may be promptly terminated and the completed roll ejected from the crop roll forming machine.
The multiple dispensing tubes are optimally employed with any type of a powered twine wrapping apparatus that can easily drive the multiple dispensing tubes. In the context of the present invention they have been specifically designed to function with automatic twine wrapping means to effect the binding of the completed crop roll in the least amount of time possible and with the least possible operator attention and involvement.
With such automatic multiple twine wrapping apparatus certain problems nevertheless still may be encountered during operation. Indeed, once an automatic twine wrapping cycle is started, all successive steps in the cycle are automatically completed one after the other. When the cycle is started, the twine dispensing arms initially are moved from a retracted home position toward the vicinity of the bale chamber inlet, at which point in the cycle, the free ends of the baling twine are permitted to enter said chamber and whereafter actual wrapping is started while that the twine dispensing arms automatically continue to move back-and-forth in the vicinity of the bale chamber inlet. It may occur, however, that one or more free ends of baling twine hesitate to enter the bale chamber or do not enter said chamber at all at said particular point in the cycle, whereby a defective or no bale wrapping at all is obtained during the further back-and-forth movement of the twine dispensing arms. This means a loss of time as the twine wrapping cycle must be repeated prior to ejecting the bale and also means a wastage of twine in the event one or more strands of twine are correctly applied while that another strand is not applied, as indeed it normally is not practical to only apply the previously defective twine during the next wrapping cycle. The foregoing problem further also requires special attention of the operator to timely detect the problem, which may be difficult when operating, e.g., during night time or in dusty conditions. It also requires active involvement of the operator to start another wrapping cycle.
It further also will be appreciated that, in case of a multiple twine dispensing apparatus, it is essential that all twines are anchored into the bale at about substantially the same instant in the twine dispensing cycle.
So far, the problems as described have been related to multiple twine wrapping means. However, it will be clear that hesitation or failure of the twine to be anchored into a bale at the appropriate point in an automatic twine dispensing cycle also is problematic when a single twine wrapping apparatus is used. The same or similar problems also may exist with twine wrapping apparatus which are not fully automatic. Indeed, in some semi-automatic twine wrapping devices the operator may have to trigger the dispensing cycle at the correct moment, whereafter the whole cycle then may be completed automatically. Hesitation or failure of the binding twine to enter the bale forming chamber at the appropriate point in the twine dispensing cycle also adversely affects in these twine wrapping devices the desired operation.
One even could conceive that the same problems may occur with a fully, manually controlled cycle. Indeed, there may be circumstances where the operator cannot see, during a twine dispensing cycle, whether twine actually is picked up by a bale in the bale chamber at the appropriate moment, whereby he thus may cause the dispensing arm to move back-and-forth across the axial dimension of the bale without any twine actually being applied on the bale.
One attempt to overcome this type of problem has been described in U.S. Pat. No. 4,182,235 relating to a semiautomatic twine wrapper for a round baler having a twine actuated switch. In one embodiment a hand switch and a twine actuated switch are provided in parallel to each other. For wrapping a bale, the hand switch is manually closed by the operator to pivot the twine dispensing arm from a home position to a location in the vicinity of the baler infeed opening for permitting twine to enter the bale chamber and start wrapping whereafter the pull on the twine closes the other switch, thus relieving the operator from the obligation to continue holding the hand switch closed during the entire wrapping cycle.
Thus, operator's attention and intervention is required to wrap a bale with this prior art mechanism. Also, the moment when the twine actuator switch takes over the function from the hand switch is rather variable and it may be difficult for the operator to notice when the hand switch precisely may be released. Finally, in the event twine is not properly picked-up by the completed bale in the bale chamber, the operator has to continue pressing the hand switch during the entire wrapping cycle until the dispensing arm returns to its home position whereafter the drive to the machine should be disengaged and the operator should manually pull a sufficient length of twine from the dispensing arm to ensure proper twine anchorage during the next cycle.
In another embodiment of U.S. Pat. No. 4,182,235, the hand-switch and the twine controlled switch are again provided in parallel to each other. A further, normally closed switch is provided in series with the hand switch and is opened by a component of the dispensing mechanism when the dispensing arm reaches a predetermined position, preferably in the vicinity of the infeed opening. Upon completion of a bale, the operator closes the hand switch to approach the dispensing arm from its home position to its said predetermined position in the vicinity of the infeed opening, at which moment the additional switch is opened thus interrupting energization of the motor of the dispensing mechanism. When twine is picked up by the rotating bale in the bale chamber and thus a pull is exerted thereon, the twine controlled switch is closed, thus re-energizing the drive to the dispensing arm, whereafter the wrapping cycle is completed automatically. However, in the event the twine is not actually anchored in the rotating bale as is desired, the mechanism is fully blocked, as indeed it cannot anymore either be reversed or moved forward. The operator thus has to stop the drive and manually pull a sufficient length of twine from the dispensing arm to ensure that, after re-energizing the drive to the machine, the twine is properly anchored and thus the cycle is continued.
It is, therefore, an object of the present invention to overcome or to attenuate the foregoing disadvantages of known twine dispensing mechanisms. The present invention is particularly useful in combination with automatic twine dispensing apparatus of both the single and multiple type but may also be applied on other twine dispensing mechanisms.